The combined search capability on the ListView is a great feature of Mendix! It solves many user requirements in projects I work on.
However, sometimes user requirements call for a grid and all of the benefits of that (spreadsheet like view, sorting, export to excel, etc.). And the search capabilities in Datagrids take a lot of explaining and getting used to by users.
While I can build a listview to look like a grid - this requires far more work than just using a datagrid. Adding the Listview combined search capability to datagrids would, IMHO, be a great addition to Mendix. Maybe it could be a developer selected option to stay with 'old school' search fields for some (legacy) datagrids or use the combined search capability.